[Carto] Overview diagram - high quality maps and memory cost

[Tyler Mitchell (OSGeo)]

Carlos - thank you for this very detailed perspective!  It fits almost
100% with my own thoughts/experience and identifies some of the main
challenges we are all likely thinking of.

Only a couple more thoughts on the output side.

When working in a traditional GIS shop, I saw us slowly switch from
using Postscript to using PDF.  While PDF was nice for previewing or
sharing maps with a client, it was horrible to handle in an efficient
manner with high resolution maps (who would expect a client to open a
64MB PDF? :)  Postscript-enabled large format printers, as well as ps
supported desktop conversion software make it still the most flexible,
in my mind.  (We also used plotter specific formats, such as HPGL for
which I used an open source library as well, but that's a different
discussion.)

In the end, I believe the postscript output option using a mixture of
vector and raster is a big win, with the option to also output in lower
resolution in other formats. 

Generally speaking, this project/idea/concept is to differentiate the
typical demand from consumers and web developers who just want a "fast
map that looks good".  In our case we are less concerned about
speed/performance and more about final product, format, etc.

Anyone have a different view?

Tyler

On Thu, 2009-08-27 at 11:27 -0700, Carlos Gabriel Asato wrote: 
> Dear all
> 
> The best method for checking if this diagram is ok is try to clarify
> the aims of this project. In other words what does mean high quality,
> high resolution large format printing in cartography.
>  
> 
> High resolution printing can be summarize as follows
> 
> resolution in dpi
> 
> 300 dpi. Good resolution for photos and small and report maps. No so
> good for printing vector data
> 
> 600 dpi. Nice resolution for photos, vector have better looking and
> forms can be better appreciation. Colors look brighter.
> 
> 1200 dpi. High quality maps. Production maps, near printing shops
> resolution ( sorry but I don not how translate
> <lang=es>"imprenta"</lang=es> ) .
> 
> 2400 dpi ???
> 
> 
> Large format printing expressed in page size standards
> 
> A4. Very common page size. Most of the users need maps at A4 pagesize.
> Good size for reports and no so elaborated maps
> 
> A3. Good size for people who needs maps in the field. On site
> surveying. Very easy to handle in field work
> 
> A2. I don have experience with this map size
> 
> A1. Typical scholarship map size. A map that a lot of people wants to
> put in a wall
> 
> A0. Most of production maps belong to this category. Topographical,
> geological, etc.
> 
> Larger sizes Continental Maps, World Maps, Instructional maps, Poster
> Like maps, special projects maps, etc.
> 
> Quality Maps
> There are too many issues related to what cartographers think what it
> is a high quality map but anyway let's first start with color.
> A cartographic system must be capable of make printings using CMYK.
> 
> 
> What I tried to explain putting resolution, page size and colors in
> table?. When I tried to introduce all of you in a very big problem.
> That is memory cost vs map quality.
> 
> Memory cost is a big issue in cartographic map production system and
> it put several constraints on:
> 
> Data Input
> Data Processing
> Data Output
> 
> 
> Data Input
> Let's start with raster data. I tried summarize constraints in few
> statements:
> "Good quality raster maps need a source of data where pixel size at
> given map scale is the same of output resolution".
> "If that condition can not be respected at least can be produced a new
> image with a zoom of 3x where the data left are interpolated"
> "Compressed images can only be used in those cases where compressing
> methods do not produce artifacts"
> "Use anyone of those two last methods if quality is not your
> objective"
> 
> I think those statements put a clear constraint about the use of WMS
> as a source of data, specially in high quality maps and also a big
> constraint about networks.
> 
> Data Processing
> Difficulties related to manipulate high amount of data, mantain
> organized them, and moving (zoom out, in, pan) the objects in the
> screen.
> 
> Data Output
> Print maps is a very difficult issue, especially due to what you see
> in you screen will not be the same you look in the paper. That is a
> problem of a specialist with universitary degree in digital printing.
> But anyway what we can tell is memory cost is also a big issue when
> people want print a map.
> 
> All the data edited and manipulated during the data processing step
> must be rasterized. It is usually rasterized to the output resolution
> using CMYK color model (32 bits). Try to remeber at what page sizes
> people want to print and what does means in terms of memory cost and
> data processing (we need to make some calculations).
> 
> A probable solution for memory cost in the Data Ouput step:
> Create a high quality postscript file and leave the problem to others.
> That is what we did.
> 
> 
> 
> 
> Gabriel Asato
> Unidad Sensores Remotos y SIG
> Servicio Geológico Minero Argentino
> (SEGEMAR)
> Av. Julio A. Roca 651 p 8 of 1
> Cdad. Autónoma de Buenos Aires
> ARGENTINA
> 
> tel 54-11-4349-3158/26
> fax 54-11-4349-3287
> 
> 
> 
> start: 2008-06-09 end: 0000-00-00 
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